Polyethylene terephthalate (PET) is particularly suitable for the manufacture of fibers, filaments and sheets. PET, however, is not generally suitable for injection molding because of the high molding temperatures (e.g. around 140.degree. C.) and the relatively long molding times required. These severe processing conditions have generally prevented the widespread use of polyethylene terephthalate for injection molding despite the fact that products molded under these severe conditions exhibit high rigidity and high heat distortion temperatures. The high mold temperatures required are beyond the equipment capabilities of many mold shops which have only water heated molds. Such molds are normally capable of temperatures no higher than about 110.degree. C. Thus, wide use of this polymer is restricted not only by the economics of its long processing cycle but also by the inability of many potential molders to process the resin.
It is an object of the present invention to provide polyethylene terephthalate compositions which can be molded at lower temperatures and more rapidly than has previously been possible. At the same time, it is an object of this invention to obtain compositions having heat distortion temperatures substantially the same as those obtained when molding under the above-noted severe conditions.